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Spring Integration Syslog Support
/*
* Copyright 2014 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.integration.syslog;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import org.springframework.util.Assert;
/**
* Parse for RFC 5424 syslog messages; when used with TCP, requires the use
* of a {@code RFC6587SyslogDeserializer} which decodes the framing.
*
* @author Duncan McIntyre
* @author Gary Russell
* @since 1.4.1
*
*/
public class RFC5424SyslogParser {
protected static final char NILVALUE = '-';
protected static final char SPACE = ' ';
protected final boolean retainOriginal;
/**
* Construct a default parser; do not retain the original message content unless there
* is an error.
*/
public RFC5424SyslogParser() {
this(false);
}
/**
* @param retainOriginal when true, include the original message content intact in the
* map.
*/
public RFC5424SyslogParser(boolean retainOriginal) {
this.retainOriginal = retainOriginal;
}
public Map parse(String line, int octetCount, boolean shortRead) {
Map map = new LinkedHashMap();
Reader r = new Reader(line);
try {
if (shortRead) {
int n = line.length() - 1;
while (n >= 0 && line.charAt(n) == 0x00) {
n--;
}
line = line.substring(0, n);
throw new IllegalStateException("Insufficient data; expected " + octetCount + " got " + (n + 1));
}
r.expect('<');
int pri = r.readInt();
r.expect('>');
int version = r.readInt();
r.expect(SPACE);
Object timestamp = getTimestamp(r);
String host = r.getIdentifier();
String app = r.getIdentifier();
String procId = r.getIdentifier();
String msgId = r.getIdentifier();
Object structuredData = getStructuredData(r);
String message;
if(r.is(SPACE)) {
r.getc();
message = r.rest();
}
else {
message = "";
}
int severity = pri & 0x7;
int facility = pri >> 3;
map.put(SyslogHeaders.FACILITY, facility);
map.put(SyslogHeaders.SEVERITY, severity);
map.put(SyslogHeaders.SEVERITY_TEXT, Severity.parseInt(severity).label());
if (timestamp != null) {
map.put(SyslogHeaders.TIMESTAMP, timestamp);
}
if (host != null) {
map.put(SyslogHeaders.HOST, host);
}
if (app != null) {
map.put(SyslogHeaders.APP_NAME, app);
}
if (procId != null) {
map.put(SyslogHeaders.PROCID, procId);
}
if (msgId != null) {
map.put(SyslogHeaders.MSGID, msgId);
}
map.put(SyslogHeaders.VERSION, version);
if (structuredData != null) {
map.put(SyslogHeaders.STRUCTURED_DATA, structuredData);
}
map.put(SyslogHeaders.MESSAGE, message);
map.put(SyslogHeaders.DECODE_ERRORS, "false");
if (this.retainOriginal) {
map.put(SyslogHeaders.UNDECODED, line);
}
}
catch(IllegalStateException e) {
map.put(SyslogHeaders.DECODE_ERRORS, "true");
map.put(SyslogHeaders.ERRORS, e.getMessage());
map.put(SyslogHeaders.UNDECODED, line);
}
catch(StringIndexOutOfBoundsException sob) {
map.put(SyslogHeaders.DECODE_ERRORS, "true");
map.put(SyslogHeaders.ERRORS, "Unexpected end of message: " + sob.getMessage());
map.put(SyslogHeaders.UNDECODED, line);
}
return map;
}
/**
* Default implementation returns the date as a String (if present).
* @param r the reader.
* @return the timestamp.
*/
protected Object getTimestamp(Reader r) {
int c = r.getc();
if(c == NILVALUE) {
return null;
}
if(!Character.isDigit(c)) {
throw new IllegalStateException("Year expected @" + r.idx);
}
StringBuilder dateBuilder = new StringBuilder();
dateBuilder.append((char) c);
while ((c = r.getc()) != SPACE) {
dateBuilder.append((char) c);
}
return dateBuilder.toString();
}
private Object getStructuredData(Reader r) {
if(r.is(NILVALUE)) {
r.getc();
return null;
}
return parseStructuredDataElements(r);
}
/**
* Default implementation returns a list of structured data elements with
* no internal parsing.
* @param r the reader.
* @return the structured data.
*/
protected Object parseStructuredDataElements(Reader r) {
List fragments = new ArrayList();
while (r.is('[')) {
r.mark();
r.skipTo(']');
fragments.add(r.getMarkedSegment());
}
return fragments;
}
protected class Reader {
private final String line;
public int idx;
private int mark;
public Reader(String l) {
line = l;
}
public void mark() {
this.mark = this.idx;
}
public String getMarkedSegment() {
Assert.state(this.mark <= this.idx, "mark is greater than this.idx");
return this.line.substring(mark, this.idx);
}
public int current() {
return line.charAt(this.idx);
}
public int prev() {
return line.charAt(this.idx - 1);
}
public int getc() {
return line.charAt(this.idx++);
}
public int peek() {
return line.charAt(this.idx + 1);
}
public void ungetc() {
this.idx--;
}
public int getInt() {
int c = getc();
if (!Character.isDigit(c)) {
ungetc();
return -1;
}
return c - '0';
}
/**
* Read characters building an int until a non-digit is found
* @return int
*/
public int readInt() {
int val = 0;
while (isDigit()) {
val = (val * 10) + getInt();
}
return val;
}
public double readFraction() {
int val = 0;
int order = 0;
while (isDigit()) {
val = (val * 10) + getInt();
order *= 10;
}
return (double) val / order;
}
public boolean is(char c) {
return line.charAt(this.idx) == c;
}
public boolean was(char c) {
return line.charAt(this.idx - 1) == c;
}
public boolean isDigit() {
return Character.isDigit(line.charAt(this.idx));
}
public void expect(char c) {
if (line.charAt(this.idx++) != c) {
throw new IllegalStateException("Expected '" + c + "' @" + this.idx);
}
}
public void skipTo(char searchChar) {
while (!is(searchChar) || was('\\')) {
getc();
}
getc();
}
public String rest() {
return line.substring(this.idx);
}
public String getIdentifier() {
StringBuilder sb = new StringBuilder();
int c;
while (true) {
c = getc();
if (c >= 33 && c <= 127) {
sb.append((char) c);
}
else {
break;
}
}
return sb.toString();
}
}
protected enum Severity {
DEBUG(7, "DEBUG"),
INFO(6, "INFO"),
NOTICE(5, "NOTICE"),
WARN(4, "WARN"),
ERROR(3, "ERRORS"),
CRITICAL(2, "CRITICAL"),
ALERT(1, "ALERT"),
EMERGENCY(0, "EMERGENCY"),
UNDEFINED(-1, "UNDEFINED");
private final int level;
private final String label;
private Severity(int level, String label) {
this.level = level;
this.label = label;
}
public int level() {
return level;
}
public String label() {
return label;
}
public static Severity parseInt(int syslogSeverity) {
if(syslogSeverity == 7) {
return DEBUG;
}
if(syslogSeverity == 6) {
return INFO;
}
if(syslogSeverity == 5) {
return NOTICE;
}
if(syslogSeverity == 4) {
return WARN;
}
if(syslogSeverity == 3) {
return ERROR;
}
if(syslogSeverity == 2) {
return CRITICAL;
}
if(syslogSeverity == 1) {
return ALERT;
}
if(syslogSeverity == 0) {
return EMERGENCY;
}
return UNDEFINED;
}
}
}
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